Electric motor



April 21, 1931. R, LEE 1,801,674

ELECTRIC MOTOR Filed July 2, 1.928

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W/ TNE' 5555 y and Patented A'pr. 21, 1931 UNITED STATES PATENT OFFICE l'ROYAL OF MILWAUKEE, WISCONSIN) ASSIGNOB '1.0 LEE ENGINEERING vRESEARCH CORPORATION, OF HILWAXEE, WISCONSIN, A CORPORATION OF WISCONSIN ELECTRIC KOTOR sp'putgaon nea my a. ma. sum l. man.

The invention relates to electric motors more particularly to motors of4 the -commutating t pe.

s An object o the linvention is to provide s: a simple and compact electric motor adaptartingthereto shunt lof the induction motor are objectionable.

'ed for operation on either direcbor alternating current, and particularly the latter,

and capable of running at a substantially tor and the fixed speed and excessive bulk Another object of the .invention is to provide a simple but effective compensating or neutralizing means for commutating t electric 'motors which is particularly well adapted for the smaller'sizes of motorsand is capable of incorporation in a motor without reducing the available winding space. g A further object is to provide a compensating winding which is self-contained with respect to any one pole area.

further object is to construct acomf pnsating winding 1by means of a metallic oop surrounding a polar projection at its inner and 'outer sideslto lie in a .plane substantially along the axis, of the projection.

er object is toiutilize the compensating loop as a means lfor attaching .the

"pole to the field yoke of the motor.

- A rther object is to form the compensatin loop in sections to permit its expeditlous venient lacement of the The invention further consists in the. sev-v eral features hereinafter set forth and more .particularly defined by the annexed claims. In the accompanying drawings, Fig. 1 is an end elevation of .anelectric motor embodying the invention, parts being broken Flg. -2 is a transverse sectional view of the motor iield frame taken o n the line 2-2 vof Fi 1.

v In 51e drawin s, the numeral 10 indicates a laminated fiel yoke `of any suitable conbetween them a rotatable pre erably diverge away attachment and to permit the con'- A pole piece and the` surroun ing field winding.

instance, each pole piece 12 away and parts being shownin section; and' struction, here shown to be annular in sha The laminations of the field yoke may secured in assembled relation in any suitable manner as` by means of rivets or bolts 11. vLaminated pole pieces 12 and 13, separate from the field yoke, are secured within .the field yoke at opposite sides thereof and have convex outer ends abutting against ,the interior surface 'of the field yoke. The laminations of each pole piece may be secured in assembled relation 1n any suitable manner as by means of rivets or bolts 14. The inner or adjacent ends of the 01e pieces are concave -to form spaced pole aces receiving commutator- The pole tips 16 from the armature quietfmotor operation.

equi ped .armature 15.

1n order to obtain ,Field windings 17 and 18'are placed about the pole pieces 12 and 13, respectively, to excite them in opposi larity and may be arranged in series wit the armature between them. y

In order to minimize the effective armature inductance to thereby secure good commutation and to permit satisfactory operation of the motor on compensating means are provided which consists in the present case of a low resistance metal loop 19 having one rtion arranged along the pole face paralleloto. the armature andan opposite portion arra d along the exterior o the field oke, the oop l g in a substantiall radialy plane passing tlilrlough the axis f t e armature. In the present 'vid'ed with a channel 20 extending lo tudinall of the pole face in'a substantia y medial ocation. Acopper bar 21'formin part lof the loop 19 fits within the channe 20 to lie substantially ush with the pole faceand projects from opposite ends of the pole piece. The field yoke 10 is rovided with the channel 22 preferably wi er than the channel 21 and extending parallel to it fto receive .the intermediate Vrtion of a U.- haped copper bar 23 whic ts therein .to lie substantially Hush with the outer surface of the yoke.

The legs ofthe U-shaped bar 23 abut against opposite ends of the alternating current,

and 13 is pro-v yoke and pole piece and Ahave forked ends -24 which receive therein the projecting ends of the copper bar 21. The ends of t e bar 21 are electrically united to the forked ends of the bar 23 in any suitable manner as by soldering or brazing.

In the-present instance, the bar 21 is utilized as a'means for securing the pole piece on the yoke. This is accomplished b providin threaded apertures 25 in ther 21 exten g in the plane of the loop' and receiving the threaded ends of attaching screws 26, the-head portions of which enter apertures in the intermediate portions of the bar 23 lying in the channel 22. In this manner, each pole piece may be secured firmly and accurately in place by means including the compensating loop. Each lield winding 17 and 18 is placed about the pole piece prior to the attachment of the pole piece to the yoke and this enables the available winding space to` be utilized to best advantage. Should it ever become necessary to replace the winding, this may be readily accomplished by removing the screws 26 and detaching the bar 21 from the ends of the U-shapedv bar 23.A It will be seen that the compensating loop can be applied to the motor in a simpleA and effective manner and'withoutTeducing the available space for the field Y The use of compensating windings has been common in single phase commutator motors but ,the means heretofore employed' for suchpur/poses have been of com lif .cated and expensive construction inter er- Aing with the effective utilization of the l available winding space. Foi-I these nea# sons, the compensating means heretofore devised have not been adapted for use in the smaller motors, especially the fractional horsepower sizes, where it is essential that any .such means be of simple and vinexpensive construction.- 'The motor construction of this invention not only provides a means whereby the same motor can be operated with a high degree of universality on both direct and single phase alternating current, but also provides a means whereby' shunt characteristics can be readily imparted to the motor to permit of a constant though ad]ustab1e motor speed on alternating current operation.

When relatively low motor speeds are desired with either the series typeof motors .or those having shunt'characteristics, suchv speeds may be readily obtained by controlling the mean value of load'current, as

inthe above United States Letters Patent No'. 1,630,394, andin such cases, employing. either interrupted or pulsating direct or alternating current, the compensating means is effective to insure ecient motor operation andl t9 avoid excessive-heating.-

l In many 11asaid field member an connecting intermediate ascisse quiring constant' speed fractional horse. p

power motors, the small and compact motors embod the invention can be emlo ed to goo advantage to replace the E ,heavy and not very'eiiicient induction motors. In such devices the motors o present invention permit the Aconstant though adjustable speed which is not possible with induction motors. In small motordriven machines intended foro eration iii.

discriminately on either alternating o r direct current, the motors of this inventionare particularly useful, especially in machinesV intended for field demonstration purposes.

What I claim as new and desire to secure by Letters Patent is:

1. In an electric motor, the combination of a field yoke having an inwardly rojecting olar portion including a polar ace, a rotata le armature co-operating with said polar face, a field winding surrounding said polar projection, compensating means including a conducting loop disposed on said polar' portion, and meansincluding said conducting loo for securing said polar portionto said yo e. l

2. In an electric motor,'the combination of a feldyoke, a pole piece within said field yoke having a channel inits polar face, a rotatable armature co-o erating with said polar face, a field winding about said pole piece, compensatin \means comprising a conducting loop, inc iiding a portion in said channel, and attac loop for securing said pole piece yoke.

'3. In an electricA motor, the combination ofva field yoke, a pole piece within said field yoke having a longitudinal channel in its polar face, a rotatable armature co-operating with said polar face, a field winding about said pole piece, compensating means comprising a conducting lloop including a portion indsaiil channel, anl mlans or securing sai e piece to sai yo e inc udin' attaching mleombers extendii1 through sai pole piece substantiall radi y thereof and entering the portion o said loop within said pole face channel.

4. In an electric motor, the combination of a field member, a pole dpiece abutting against Y having a channel in its polar face, a rectangular compensating loop for said pole piece having one side portion disposed in said channel and having an opposite side portiondisposed on the outside said field member,- and attac screws (points of t e oppoloop and passing site side portions of sai through said pole piece and eld member to f clamplaid po e piece to said field member.

5. an electric motor, the combination of a f ield member, a pole (piece abutting against said ield member an having a channel in 0 f the means engaging said loop for said pole iece having one side portion disposed in sa1d channel and having an opposite side portion disposed on the outside of said field member, said first-named side 5 portion having tapped openings formed therein at intermediate points, and attaching screws connecting the opposite side portions of said loop and threaded into said tapped openings for clamping said pole piece to said 1o field member.

6. In an electric motor, the combination of a field member, a pole piece abutting against said member and having a longitudinal channelin its polar face, a metal bar of low resistance disposed in said channel and having its opposite ends projecting therefrom, a U-shaped metal strap of low resistance saddled over said eld member to engage the outer side thereof and having forked ends yembracing' and secured to the opposite ends of said bar to form a compensating loopfor said pole piece, and means en aging said bar and distinct from the ends o? said strap for securing said pole piece to said iield member. In testimony whereofl aix my signature.

ROYAL LEE.

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